Terminal-testing unit for spark plugs



Nov. 22, 192 7.

H. J. STRAHAN TERMINAL TESTING UNIT FOR SPARK PLUGS Fi led June 15. 1926 INVENTOR J-L. .Ifi'traham WITNESSES ATTORNEYS Patented Nov. 22,1927

E" 's'rr HARRY 'JISTiRAHANQQ -F E YORVKQVN TERMINAL-TESTih G time ron SPARK rnues.

Application filed June 15,

This invention relates to accessories for spark plugs and has particular reference to a separable terminalunit by means of which the testing of a spark plug with theinotor running is greatly facilitated.

More specificallypthe invention comprehends a device tor facilitating the testing of spark plugs which consists of an. insulated terminal unit'to which the, conductor-wire is attached, said unit being. provided with means for establishing detachable frictional electrical connection between, the binding post or central electrode otthe plug and conductor wire to afford an insulated grasping means for c onvenie'ntlyefiecting the removal, testing, and replacement ofth'ennit with the motor intoperation, while precluding any shock or injury to the'person-"conducting the test, andffur'ther, eliminating the necessity of using tools or other instru} ments for such purposes. y

The invention furthermore comprehends a terminal unit of the character set forth which is extremely simple in its construction, inexpensive to manufacture, and which is highly efficient in its purpose.

lVith the above recited and other objects in view, reference is had to the following specification and accompanying drawingsin which there is exhibited one example or embodiment of the invention which is in no way intended as a limitation uponthe scope of the appended claims as it is to be clearly understood that variations and modifications which properly fall within the scope of said claims may be resorted to when found (3X1 pedient.

In the drawings- Figure 1 is a side view of a spark plug equipped with a terminal unit constructed in accordance with the invention and illustrating the same disconnected and spaced from the plug to accomplish the testing operation;

Fig. 2 is an enlarged fragmentary vertical sectional view of the unit applied to the plug binding post or central electrode:

Fig. 3 is a perspective view of the inner binding'post gripping and conductor element removed from the terminal unit.

Referring to the drawings by characters of reference, A designates a spark plug of any ordinary construction. which is pro vided with the usual upwardly projecting threaded stem B constituting the/central 1926. semi No. name; i

electrode and serving as a-bindingpost'. In

lieu-=otplacing the terminal Got the conductor wire Dover the stem B and em ploying abmdmg nutto clamp the'same in place as is the common practice, the present invention comprehends the use of a terminal 2 unit tor the purpose or" removably connecting theronductor wire terminal with the t binding post so as toffacilitate'the testing ,ot the plugfiwithout the use of tools.

The terminal unit constituting the present invention, consistsoi a body 10 constructed of an insulating material'and having an en.-

larged-grasping head 11 at one end. At its opposite end the body is provided with an inwardly extending bore12 of a length exceeding the length of the threaded stem or binding post B andof a diameter greater ,thau the,diameterof said stem. Theybody 10 is further provided with a laterally projecting tubular boss or arm 13, the bore 1% of which isof a diameter to snugly receive the insulated conductor D. The bore 14 is constricted at its inner end, as at 15, and the constricted portion of the bore communicates with the bore 12 of themain body 10. Within the bore 12, a sleeve-like element 16 is fitted, the said element having an aperture 17, which is designed to aline withthe c0n striated portion 15 of the bore 14 so as to receive the uninsulated terminal C of the conductor wire D after which the extremity of the wire terminal is upset or burred as at E. by the insertion of a suitable tool inserted through the bore'12. The sleeve-like element 16 is formed with circumferentially spaced inwardly arehed,depending fingers 18 which may be producedby slitting the element 16 from its end and removing aL ternate portions between the slits. The ele ment 16 is preterablyof a resilient conducting material and when thefingers, which are bowed or arched inwardly, are innormal position, they are spaced apart a distance less thanthe diameterof the threaded stem B,

sothat when the bore 12 of the body 10 is positioned over the threaded stem B, a fricplug, whereby the conductor wire is electrically connected with. the plug.

tional gripping action will be set up to retain the unit in correlation to the spark When it is desired to test thepl ug, the

l unit is grasped and withdrawn from 1ts frictionally connected relation to the stem B, as illustrated in Fig. 1, and properly spaced .to produce" a spark gap for accomplishing the testing operation. It is obvious'that this may be done with the motor running without fear of shock or injury to the person making the test, and it is clearly apparent that the testing operation may be accomplished in a minimum of time and without the necessity of employing tools.

VVhat is claimed is:

1. A terminal testing unit for spark plugs, comprising a body of insulatin material havingan enlarged grasping hea atone of its ends and a socket in its opposite end, and a frictional gripping element Within the socket electrically connected with the conductor wire and adapted to frictionally engage and maintain the unit electrically connected with the spark plug binding post, said element comprising a sleeve-like body and annular inwardly bowed resilient fingers normally spaced apart a distance less than the diameter of the spark plug binding post, the body of said unit having a lateral tubular boss of insulating material having its bore constricted at the inner end and communicating with the socket of the body, said boss adapted to receive the conductor Wire with the terminal connected with said element-,to establish an electrical connection with and to retain said element within the socket of the body.

2. A terminal testing unitfor spark plugs, comprising a body of insulating material having a socket in one of its ends, and a frictional gripping element within the socket electrically connected with the conductor wire and adapted to frictionally engage and maintain the unit electrically connected with the spark plug binding post, said elementcomprising a sleeve-like body and annular inwardly-bowed resilient fingers normally spaced apart a distance less than the diameter of the spark lug binding post, the body of said unit having a lateral tubular boss of insulating material having its bore constricted at the inner end and communicating with the socket of the body, said boss adapted to receive the conductor wire with the terminal connected with said element, the said element having an aperture adapted to register with the constricted end of the bore of the boss to receive therethrough the conductor wire terminal, the protruding extremity of which terminal is upset to retain the same in place and to lock the element in the socket of the body.

HARRY J. STRAHANQ 

